Why does a boiled egg become hard and solid

Question: Why does a boiled egg become hard and solid
- Keywords:
  boil,
  egg,
  solid
Asked by Aaron to Yannis, Elaine on 14 Nov 2017. This question was also asked by 595fddk47.
- Elaine Kennedy answered on 14 Nov 2017:
  
  The heat used to boil the egg denatures the proteins which then clump together and become solid which is why a boiled egg becomes solid and hard.

Question: Why does a boiled egg become hard and solid